最近学习mybatis时发现一个问题，从threadlocal里取出的sqlsession是null 是null

[qq_38841290]

SqlSessionUtil工具类

public class SqlsessionUtil {
    private static SqlSessionFactory sqlSessionFactory;
    private static ThreadLocal<SqlSession> threadLocal;
    //类加载时初始化sqlSessionFactory
    static {
        try {
            InputStream inputStream= Resources.getResourceAsStream("mybatis-config.xml");
            sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
        threadLocal=new ThreadLocal<SqlSession>();
    }

    /**
     * 得到sqlsession
     * @return
     */
    public static SqlSession getSqlCurrentSqlsession(){
        SqlSession sqlSession=threadLocal.get();
        if (sqlSession==null){
            sqlSession=sqlSessionFactory.openSession();
            threadLocal.set(sqlSession);
        }
        return sqlSession;
    }

    /**
     * 回滚
     * @param sqlSession
     */
    public static void rollBack(SqlSession sqlSession){

        if (sqlSession!=null){
            sqlSession.rollback();
        }
    }

    /**
     *释放资源
     * @param sqlSession
     */
    public static void close(SqlSession sqlSession){
        if (sqlSession!=null){
            sqlSession.close();
            threadLocal.remove();
        }

    }


}

事务处理器TransactionHandler

public class TransactionHandler implements InvocationHandler {
    //目标对象
    private Object target;
    //构造器

    public TransactionHandler(Object target) {
        this.target = target;
    }
    //得到代理对象
    public Object getProxy(){
        return Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass().getInterfaces(),this);
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        SqlSession sqlSession=null;
        Object invoke=null;
        try{
            //手动提交事务
             sqlSession = SqlsessionUtil.getSqlCurrentSqlsession();
            //dowork
             invoke=method.invoke(target,args);
            //提交事务
            sqlSession.commit();
        }catch (Exception e){
            //回滚
            SqlsessionUtil.rollBack(sqlSession);
            e.printStackTrace();

        }finally {
            SqlsessionUtil.close(sqlSession);
        }

        return invoke;
    }


}

UserDao 和UserDaoImpl

public interface UserDao {

    /**
     * 保存用户
     * @param usre
     * @return
     */
  int save (User usre);
}
public class UserDaoImpl implements UserDao {


    @Override
    public int save(User user) {
        return SqlsessionUtil.getSqlCurrentSqlsession().insert("save",user);
    }
}

测试类

   public  void TESTUTILS(){
        UserDao userDao=(UserDao) new TransactionHandler( new UserDaoImpl()).getProxy();
        User user =new User();
        user.setSex("男");
        user.setName("的发生");[code=java]

int i=userDao.save(user);
System.out.println(i);
}[/code]

调试发现 第二次从threadlocal中取出的sqlsession是null
调试 第一次进入getSqlCurrentSqlsession()：

    public static SqlSession getSqlCurrentSqlsession(){
        SqlSession sqlSession=threadLocal.get();    //defaultsqlsession@1871
        if (sqlSession==null){
            sqlSession=sqlSessionFactory.openSession();
            threadLocal.set(sqlSession);
        }
        return sqlSession;
    }

第二次进入发现从threadlocal中取出来的是null,所以又重新创建了一个sqlsession 最后报错

    public static SqlSession getSqlCurrentSqlsession(){
        SqlSession sqlSession=threadLocal.get();     //defaultsqlsession@1875
        if (sqlSession==null){
            sqlSession=sqlSessionFactory.openSession();
            threadLocal.set(sqlSession);
        }
        return sqlSession;
    }

报错代码为：
org.apache.ibatis.exceptions.PersistenceException:
### Error committing transaction. Cause: org.apache.ibatis.executor.ExecutorException: Cannot commit, transaction is already closed
### Cause: org.apache.ibatis.executor.ExecutorException: Cannot commit, transaction is already closed
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:227)
at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:218)
at com.li.utils.TransactionHandler.invoke(TransactionHandler.java:35)
at com.sun.proxy.$Proxy6.save(Unknown Source)
at com.li.test.TESTUTILS(test.java:58)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:69)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:48)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:292)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
Caused by: org.apache.ibatis.executor.ExecutorException: Cannot commit, transaction is already closed
at org.apache.ibatis.executor.BaseExecutor.commit(BaseExecutor.java:239)
at org.apache.ibatis.executor.CachingExecutor.commit(CachingExecutor.java:119)
at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:224)
... 28 more
打印了一下线程，发现始终都是main线程
DEBUG - PooledDataSource forcefully closed/removed all connections.
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
Thread[main,5,main]
DEBUG - Opening JDBC Connection
DEBUG - Created connection 2109839984.
DEBUG - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.Connection@7dc19a70]
DEBUG - ==> Preparing: insert into t_user(name,sex) values(?,?)
DEBUG - ==> Parameters: 的发生(String), 男(String)
DEBUG - <== Updates: 1
Thread[main,5,main]
DEBUG - Committing JDBC Connection [com.mysql.jdbc.Connection@7dc19a70]
DEBUG - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.Connection@7dc19a70]
DEBUG - Closing JDBC Connection [com.mysql.jdbc.Connection@7dc19a70]
DEBUG - Returned connection 2109839984 to pool.
Thread[main,5,main]
Thread[main,5,main]
org.apache.ibatis.exceptions.PersistenceException:
### Error committing transaction. Cause: org.apache.ibatis.executor.ExecutorException: Cannot commit, transaction is already closed
### Cause: org.apache.ibatis.executor.ExecutorException: Cannot commit, transaction is already closed
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:227)
at org.apache.ibatis.session.defaults.DefaultSqlSession.commit(DefaultSqlSession.java:218)
at com.li.utils.TransactionHandler.invoke(TransactionHandler.java:35)
at com.sun.proxy.$Proxy6.save(Unknown Source)
at com.li.test.TESTUTILS(test.java:58)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:69)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:48)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:292)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.jav

[编号灬9527]

项目打个包丢百度网盘分享下，有点意思， 不过看日志，connection已经被关闭了 DEBUG - Committing JDBC Connection [com.mysql.jdbc.Connection@7dc19a70] DEBUG - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.Connection@7dc19a70] DEBUG - Closing JDBC Connection [com.mysql.jdbc.Connection@7dc19a70] DEBUG - Returned connection 2109839984 to pool. mybatis获取connection，通过Transaction接口，最终落到datasource获取connection，如果connection的autoCommit属性是True，那估计手动提交就翻车了

[qq_38841290]

我重新建了个项目发现没问题

[qq_38841290]

链接：https://pan.baidu.com/s/1-dE6RojPOS3lWzrbfyjx2Q 提取码：79wx 复制这段内容后打开百度网盘手机App，操作更方便哦

[qq_38841290]

还是不行 懵逼了

[Mi_Manchikkk]

@编号灬9527 您用的idea是哪个版本

[编号灬9527]

拿你代码跑了下 没问题

[qq_38841290]

我一直都会得到两个 sqlsession 报错 太浪费时间了不研究了

[qq_38841290]

我之前重新创了一个项目 发现没问题 之后就配置了一下tomcat 不是maven上的插件(debug不习惯) 就又不行了

[maradona1984]

删了SqlsessionUtil.close(sqlSession);

[maradona1984]

感觉不对,为啥会拿到已经关闭的sqlsession对象才是问题所在,这个有点怪异